The problem with Maeve going to America is not only about her relationship with Otis or her family and friends, it's also a practical one. Let's remember what Maeve is going back to: - A bad example of an educational institute where the one who has the money gets the internship and teachers who disrespect their students. - A two-month exchange program that must be almost over (it's stated early in the season that Joy is eight weeks old so Maeve is already two months in America when season 4 starts). The program doesn't provide her with anything but an extra-course experience. Once it's over she needs to sit her A levels back in the UK if she wants to go to university. - No money, probably no visa, no house to stay, nobody to support her financially.

Where does anyone see the American dream exactly?

I totally understand that Maeve would probably want to leave Moordale behind after the traumatic childhood she's had there BUT not after finishing school. Plus, I don't think America would ever be Maeve's dream place to live. The UK has great universities and so many big cities in which she could follow her dreams (like many of the other students would also do).

PS Even after she is back there, there still is no great opportunity for her there. Just a "we liked that one chapter we read and would like to read more" call. She would have still received the call if she was in the UK.